diff --git a/rag_refresh.py b/rag_refresh.py
index c937c4f..759a282 100644
--- a/rag_refresh.py
+++ b/rag_refresh.py
@@ -91,7 +91,13 @@ for name in DOCS:
         print(f"rag_refresh: upload failed for {name}: {e}", file=sys.stderr)
         continue
     fid = resp.get("id")
-    code, _ = api(f"/api/v1/knowledge/{KB_ID}/file/add", {"file_id": fid})
+    # attach can 400 transiently right after upload (file still processing) — retry
+    code = None
+    for attempt in range(3):
+        code, _ = api(f"/api/v1/knowledge/{KB_ID}/file/add", {"file_id": fid})
+        if code == 200:
+            break
+        time.sleep(5 * (attempt + 1))
     if code != 200:
         print(f"rag_refresh: attach failed for {name}: {code}", file=sys.stderr)
         continue